Thanks to some inviting design strategies, a foyer becomes more than a place to dump a coat—and can even host a cocktail party. Hot toddy, anyone?

AN ENTRYWAY IS a home's decompression chamber—a place that invites guests to escape the world and shed quotidian worries, not to mention outdoor gear. In his apartment in a landmark Manhattan condominium, interior designer Michael Barry transformed an existing dining room into an entrance hall that's big enough to do all that and serve other functions, too.

The room's three doorways connect to a vestibule, an expansive living room and a marble-clad kitchen—and Mr. Barry, who works with the sort of A-list clients who...